Narrative:

I was instructing in the rear cockpit with an experienced student in the front of a schultzer SGS2-33 glider being towed behind a cessna L19 tow plane. Climbing through 1000 ft AGL, I was PF when the student called out 'traffic!' and pointed high and left. Immediately another L19 tow plane came into view from a 10 O'clock position in a steep fast descent and very close. I released the tow rope and banked hard to the right to avoid the imminent collision between the 2 L19's. The descending L19 made an abrupt correction and passed above and slightly between the tow plane and glider. All 3 aircraft then landed normally. In the discussion that followed it was discovered that the towing L19 pilot was unaware of the traffic until feeling its wake. Contributing factors were the high-wing blind spots of both the glider and tow plane, and the intersecting climb out and landing pattern entry rtes and altitudes. As for human performance considerations, in the future I will give students the authority/authorized to assume immediate control if required by timeliness (the front cockpit has fewer blind areas). I will also be more vigilant in this traffic area. Both L19 pilots agreed that a more aggressive see-and-avoid attitude is appropriate in general at this airport.

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Original NASA ASRS Text

Title: INSTRUCTOR PLT OF A GLIDER TRAINING FLT TOOK EVASIVE ACTION TO AVOID A DSNDING TOW ACFT BY RELEASING HIS TOW OF HIS TOW ACFT AND BANKING SHARPLY. NMAC.

Narrative: I WAS INSTRUCTING IN THE REAR COCKPIT WITH AN EXPERIENCED STUDENT IN THE FRONT OF A SCHULTZER SGS2-33 GLIDER BEING TOWED BEHIND A CESSNA L19 TOW PLANE. CLBING THROUGH 1000 FT AGL, I WAS PF WHEN THE STUDENT CALLED OUT 'TFC!' AND POINTED HIGH AND L. IMMEDIATELY ANOTHER L19 TOW PLANE CAME INTO VIEW FROM A 10 O'CLOCK POS IN A STEEP FAST DSCNT AND VERY CLOSE. I RELEASED THE TOW ROPE AND BANKED HARD TO THE R TO AVOID THE IMMINENT COLLISION BTWN THE 2 L19'S. THE DSNDING L19 MADE AN ABRUPT CORRECTION AND PASSED ABOVE AND SLIGHTLY BTWN THE TOW PLANE AND GLIDER. ALL 3 ACFT THEN LANDED NORMALLY. IN THE DISCUSSION THAT FOLLOWED IT WAS DISCOVERED THAT THE TOWING L19 PLT WAS UNAWARE OF THE TFC UNTIL FEELING ITS WAKE. CONTRIBUTING FACTORS WERE THE HIGH-WING BLIND SPOTS OF BOTH THE GLIDER AND TOW PLANE, AND THE INTERSECTING CLB OUT AND LNDG PATTERN ENTRY RTES AND ALTS. AS FOR HUMAN PERFORMANCE CONSIDERATIONS, IN THE FUTURE I WILL GIVE STUDENTS THE AUTH TO ASSUME IMMEDIATE CTL IF REQUIRED BY TIMELINESS (THE FRONT COCKPIT HAS FEWER BLIND AREAS). I WILL ALSO BE MORE VIGILANT IN THIS TFC AREA. BOTH L19 PLTS AGREED THAT A MORE AGGRESSIVE SEE-AND-AVOID ATTITUDE IS APPROPRIATE IN GENERAL AT THIS ARPT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.